Serial lactate measurements are reliable and may be useful as a prognostic marker in critically ill patients. Differences in its levels, depending on the sample site, can lead to misinterpretation and inadequate treatment. The primary objective of this study is to evaluate the relationship between lactate levels in different compartments of the body, such as peripheral venous, central venous and arterial blood in patients with severe sepsis and septic shock. Secondarily, we aimed at evaluating the impact of them in patient management.

This transversal study included patients with severe sepsis or septic shock with a central venous line in place. Blood from a peripheral venous puncture, central venous line and arterial line were collected, at the same timepoint each 12 hours. Peripheral lactate collection was performed carefully with the left superior limb garroted for a maximal of 2 minutes. Data were analysed by linear correlation test, and a Bland–Altman test was done to verify the degree of agreement between values from different samples. A P value <0.05 was considered significant.

Fifteen patients were enrolled, with a mean age of 57.8 years (eight males and seven females), APACHE II score of 15.3 ± 5.0 and SOFA score of 7.13 ± 3.39. A total of 129 samples were available for analysis. The linear correlation between arterial and central venous lactate levels showed an r2 = 0.66 (95% CI: 0.71–1.12). However, Bland–Altman had a mean ± standard deviation bias of 1.25 ± 5.0. Results were similar for arterial and peripheral venous lactate with an r2 = 0.85 (95% CI: 0.97–1.27) and a bias of -2.44 ± 5.0. Clinical agreement between arterial and central venous blood was 90%, arterial and peripheral blood was 71% and central venous and peripheral blood was 64%.